This invention relates generally of plasma spray deposition of nanostructured and amorphorus ceramic coatings, and, more particularly, to the deposition of thick films in solid oxide fuel cell (SOFC) stack assemblies produced by such plasma spray depositions.
Various techniques are known for producing and consolidating metastable oxide-ceramic powders to obtain bulk materials with nanocrystalline or nanocomposite structures. In one method, metastable nano-sized particles of single component oxides, prepared by vapor condensation are consolidated by high pressure sintering to form nanocrystalline products. In another method, metastable micro-sized particles of multi-component oxides, prepared by melt quenching, are consolidated by pressure assisted sintering to form nanocomposite products. Another technique is to plasma spray nanostructured coatings, including metal-metal, metal ceramic and ceramic-ceramic systems, primarily for wear and thermal barrier applications. Furthermore, there are techniques for using liquid solutions, particle slurries, and fine particle aggregates as feed materials in plasma spraying.
An important distinction from the prior art is the use of rapid quenching methods to obtain far from equilibrium or metastable structures in the spray deposited materials. The methods involve feeding fine particles or aerosols into high enthalpy DC- or RF-plasma torches, preferably with axial feed systems, followed by rapid quenching of the resulting homogeneous particles on chilled substrates to form uniform metastable deposits.
Materials produced by these processes have a variety of applications, including medical devices. However, certain characteristics of the materials, such as their non-uniformity, have limited their commercial use.
It is known to make solid oxide fuel cells (SOFCs) from porous ceramic or composite electrodes and a dense ceramic electrolyte. However, such fuel cells have not achieved wide commercial success in view of the cost of manufacture and the high operating temperatures that are required for use. It would be useful to develop solid oxide fuel cells that can be manufactured economically and can be operated at lower temperatures than prior known fuel cells.
Accordingly, it is an object of the present invention to provide a novel method for making nanostructured and amorphous solid-oxide fuel cells.
Another object of the invention is to provide such fuel cells having enhanced oxygen ion transport and increased electrochemical activity as compared to prior known structures.
Another object of the invention is to provide electrolyte and electrode layers with desired far from equilibrium and metastable structures.
Yet another object of the invention is to provide a novel method of economically producing such fuel cells in large quantities.
Another object is to provide such fuel cells with improved efficiency.